144p Test Suite

The 240p Test Suite is a homebrew application for video game consoles that helps evaluate compatibility of upscalers and other video processors, either stand-alone or built into a TV, with retro consoles' video.

MDFourier is a tool to compare audio signatures and generate graphs that show how they differ. A tone generator produces a signal for recording from the console, and the analysis program compares the frequencies to a reference recording and displays the results.

This program is a port of Artemio Urbina's 240p Test Suite to the Game Boy, as a way of learning the Game Boy CPU. It also contains an MDFourier tone generator.

Build requirements: RGBDS, Python 3, Pillow, and GNU Make

Usage

To run this on a Game Boy, load the ROM onto your EverDrive-GB or Catskull cartridge.

In menus and help:

• Control Pad ⬅➡: Turn page
• Control Pad ⬆⬇: Move cursor
• A Button: Choose option
• B Button: Go to previous menu
• Start Button: Show help for menu

In an activity:

• Control Pad, A, Select: Control activity
• Start Button: Show help for activity
• B Button: Close activity

Some tests are exclusive to Game Boy Color and Super Game Boy.

To show help for any test, press Start or read src/helppages.txt. Gus, the character at left, was an esports instructor until game publishers cracked down on the esports academies in June 2012 and July 2013. Then he became a home theater installer.

To skip straight to MDFourier tone generator, hold the Start Button as the console maker's logo disappears.

Versions

The Game Boy outputs a progressive video signal with 144 lines of picture. The original Game Boy and Game Boy Pocket have a passive matrix STN LCD panel that displays four shades of gray. The Super Game Boy accessory maps these gray shades to colors. The Game Boy Color has a TFT panel with 32 levels per RGB channel. Super Game Boy and Game Boy Player accessories act as scalers to allow use of Game Boy software with a television.

The Game Boy display works by absorbing light instead of emitting it. Because of this "subtractive" nature, as well as the overall reduced contrast and other display artifacts on monochrome handhelds, many tests allow inverting grays with the Select Button.

To keep positive and negative voltages balanced, an LCD inverts each pixel's phase on alternate frames. Game Boy displays alternate this phase by row. Thus slight level differences between a pixel and its inverted counterpart can look like interlace. (See "LCD monitor technology and tests" by W. Andrew Steer.)

Though the NES version of 240p Test Suite uses about 40 KiB of ROM data, the Catskull cartridge is limited to 32 KiB. Fortunately, the graphics for several tests are smaller than on a 240p platform, which makes the menu, Linearity, Sharpness, Drop Shadow, and Scroll Test smaller. I managed to make some tests' help text more concise. Easily readable VRAM helps, as does the 8080 family's better code density for anything that doesn't use structs or parallel arrays.

A Game Boy Advance port is also available.

Artemio Urbina maintains the upstream suite on five platforms:

• Sega Genesis (Mega Drive), as cartridge and Sega CD
• TurboGrafx-16 (PC Engine), as HuCard, CD-ROM2, and Super CD-ROM2
• Super NES (Super Famicom), as cartridge
• Sega Dreamcast, as MIL-CD
• Nintendo GameCube and Wii, as GameCube disc and DOLs for SD loader

The name

NTSC analog televisions were designed for interlaced video conforming to CCIR System M and System J, which specify an analog video signal with 15.734 kHz by 59.94 Hz sync frequencies and 480 out of 525 lines. Most video game consoles before the Dreamcast bent the rules, producing progressive video with 240 out of 262 or 263 lines. This was out of spec yet within TVs' tolerances. This sort of signal came to be called "240p" video.

Some handhelds drive their internal LCD with System M-like timings. For example, the Game Gear's display has 144 active lines, which are centered in the 240p output of EvilTim's Game Gear RGB mod. The Game Boy, on the other hand, uses an incompatibly slower 9.2 kHz horizontal sync. Super Game Boy has to use a frame buffer to convert the timing to 240p or 480i, which adds lag. This is why the Game Boy port is renamed.

Limits

• Linearity: No support for non-square NTSC or PAL pixel aspect ratios when used through Super Game Boy.
• Gradient and SMPTE color bars are not available on SGB.
• Sound Test: No "Crowd" because GB PCM is limited to 4 bits and very fiddly to get right without buzzing artifacts.
• Alternate 240p/480i: SGB and GB Player offer no control over the host systems' interlace modes except through SGB JUMP.
• The IRE levels of the Super NES and Nintendo GameCube video output have not yet been measured.

Contributors

• Concept: Artemio Urbina @Artemio
• Code: Damian Yerrick @PinoBatch
• Main menu graphics: Damian Yerrick
• Portrait in Shadow sprite test: darryl.revok
• Hill zone background: mikejmoffitt
• Extra patterns and collaboration: Konsolkongen & shmups regulars

If you're interested in contributing to the Game Boy port, you're invited to post in its NESdev thread or GBDev thread or join the gbdev chat server on Discord or Matrix.

Copyright 2011-2018 Artemio Urbina
Copyright 2018-2021 Damian Yerrick

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.